Dynamics of the meningeal CD4(+) T-cell repertoire are defined by the cervical lymph nodes and facilitate cognitive task performance in mice.

The traditional view of the central nervous system (CNS) as an immune-privileged organ yielded a longstanding perception of such interactions—as seen for example in multiple sclerosis (MS) —as intrinsically destructive. This notion is changing with the identification of several homeostatic functions attributable to beneficial T-cell/CNS interaction , for example in hippocampal-dependent learning and stress response paradigms , and in models of neurodegeneration and CNS injury . Here we provide insights into the maintenance, and dynamics of the meningeal T-cell repertoire. We show that meningeal T-cell composition is coupled to the CNS-draining deep cervical lymph nodes (dCLNs), whose surgical removal interrupted the normal flow of meningeal T-cells and resulted in cognitive impairment.